Stabilization of textile fibres

ABSTRACT

A method of treating wool or cotton fibers to improve their resistance to, and recovery from, deformations encountered, for example, in the wrinkling of garments during wearing and in the deterioration of dimensions and shape of such articles during use or washing, which method comprises subjecting the fibers to a heat treatment while maintaining the regain within the range corresponding to the range of relative humidities encountered under normal use and for a period sufficient to allow the rearrangement of at least a proportion of the hydrogen bonds in the fibers in their minimum energy configuration. The method may form part of a process for rendering the articles dimensionally stable to machine washing and drying, in accordance with which the fibers treated as above are reacted with a reagent capable of forming permanent cross-links between reactive groups in the fibers.

United States Patent Delmenico et al.

[ 1 Feb. 1, 1972 [73] Assignee:

154] STABILIZATION OF TEXTILE FIBRES Commonwealth Scientific and Industrial Research Organization, East Melbourne, Victoria, Australia [22] Filed: Dec. 4, 1969 [21] Appl.No.: 882,276

[30] Foreign Application Priority Data Dec. 5, 1968 Australia ..47352/68 [52] US. Cl ..8/127.5, 8/1276, 8/128, 8/116, 8/1 16.2, 8/1163, 8/116.4,117/139.4 [51] Int. Cl. ..D06m 3/02, D06m 3/06, D06m 3/10 [58] Field oiSearch ..8/116,l16.3, 120, 127.6, 127.5, 8/ 128, 130.1

{56] References Cited UNITED STATES PATENTS 3,293,071 12/1966 Pcloquin et al. ..8/l16 X 3,386,193 4/1968 Tewksbury et al ..8/1 16.3 X

OTHER PUBLICATIONS Watt, Textile Research Journal, June 1960, pp. 443- 450. Textile Research Journal, Nov. 1963, pp. 958 and 959.

Primary Examiner-George F. Lesmes Assistant Examiner-H. Wolman Attorney-Stowell & Stowell [5 7] ABSTRACT A method of treating wool or cotton fibers to improve their resistance to, and recovery from, deformations encountered, for example, in the wrinkling of garments during wearing and in the deterioration of dimensions and shape of such articles during use or washing, which method comprises subjecting the fibers to a heat treatment while maintaining the regain within the range corresponding to the range of relative humidities encountered under normal use and for a period sufficient to allow the rearrangement of at least a proportion of the hydrogen bonds in the fibers in their minimum energy configuration.

The method may form part of a process for rendering the articles dimensionally stable to machine washing and drying, in accordance with which the fibers treated as above are reacted with a reagent capable of forming permanent cross-links between reactive groups in the fibers.

10 Claims, No Drawings STABILIZATION OF TEXTILE FllBRES This invention relates to a method for treating textile fibers, in particular wool, to improve their resistance to, and recovery from, deformations encountered, for example, in the wrinkling of garments during wearing, in the deterioration of dimensions and shape of such articles during use or washing, and during processing and manufacturing operations. The method can also form part or all of a process for permanently setting textile fibers or articles made therefrom and for rendering them dimensionally stable to machine washing and drying.

Throughout the specification, the method of our invention will be explained and elucidated with particular reference to wool and cotton fibers, but is is to be understood that the method is applicable to other keratinous and cellulosie fibers and to mixtures thereof, and to fibers made 'from other polymeric materials in which hydrogen bonds contribute significantly to the stability of the fiber structure and which undergo molecular rearrangement, either temporary or permanent, for example under the action of heat, moisture or degradative or swelling solvents or chemicals. Such fibers will be hereinafter referred to as fibers of the type described.

Methods for the dimensional stabilization of wool and cotton fibers, in a desired geometrical configuration, have been and still are the subject of considerable study. While many quite successful processes have been developed, there is still a need to provide improved techniques which give further improvements in the performance of such textile articles under adverse conditions. One area of continuing research is concerned with improving the resistance of wool and cotton articles to wrinkling and creasing, particularly under conditions of high humidity and temperature. The present invention is a direct result of research aimed at providing improvements in this latter area, but it will be apparent to those skilled in the art that the advantageous effects of the present invention are not limited to the area of wrinkling and wrinkle recovery nor to use on any one type of polymeric material.

It is known that the ability of wool to recover from wrinkling at high-relative humidities improves considerably if the wool is stored for several years under ambient conditions. We have now found that this effect can be greatly accelerated and can be reproduced at will be raising the temperature of the wool under conditions which do not cause loss of moisture from the wool. Within limits the effect can be accelerated further by simultaneously increasing the regain of the wool. (Regain is defined as the moisture content, based on the dry weight of the wool and is related to the relative humidity of the atmosphere in contact with the wool.)

We have also observed that wool treated in this manner possesses a degree of wrinkle recovery which is considerably higher than wool which has not been thus treated. There are i also appreciable improvements in other physical properties of the wool fibers. Our investigations have indicated that this phenomenon is a single fiber property and we believe that it results from the rearrangement of labile hydrogen bonds within the wool fibers to other more stable (i.e., low energy configurations under conditions of increased temperature and/or regain. MOre precisely, it appears that conditions of increased temperature and/or regain bring about rupture of strained hydrogen bonds and as the temperature and/or regain are slowly reduced the hydrogen bonds progressively reform and in so doing take up configurations possessing the lowest possible energy. Thus, the process is somewhat akin to the annealing of glass or other said range and for a period sufficient to allow the rearrangement of at throughout this specification we will use the term annealing" to describe the phenomenon.

Broadly stated, in a first main aspect, the present invention provides a method for increasing the resistance to, and recovery from deformation of textile fibers of the type described within a range of relative humidities which process comprises subjecting the fibers to a heat treatment while maintaining the regain at a value corresponding to a relative humidity within the rearrangement of at least a proportion of the hydrogen bonds in the fibers to theirminimum energy configuration.

MOre specifically the method of the invention comprises heating wool fibers, while maintained at a regain within the range corresponding to the range of relative humidities encountered under conditions of normal use, to a temperature sufficient to bring about the rupture of at least a proportion of the intrafiber hydrogen bonds and cooling the wool to ambient conditions at a rate which is sufficiently low to allow the reformation of said hydrogen bonds in their minimum energy configuration.

In general, the wrinkling of wool is most pronounced at high regains, i.e., under conditions of high-relative humidity, such as are encountered in many parts of the world during the summer months. Accordingly, it is preferable in the practice of the invention to carry out the annealing treatment at highrelative humidities i.e., about to percent R.H. although values above or below this figure may be used. In practice, quite good results can be obtained by annealing at relative humidities as low as 60 to 70 percent R.H. but the wrinkling performance at high humidities of wool articles thus treated is then improved to a noticeably lesser degree than if annealing had been carried out at a higher relative humidity. However, since the wrinkling behavior of wool is good at low-relative humidities, there is usually little need to anneal at low-relative humidities.

The actual treatment conditions may vary considerably, the three variables'of time, temperature and relative humidity being interrelated and to an extent complementary. Thus, in the method of the invention wool fibers may be annealed by holding for several weeks at 85 percent relative humidity (R.H.) and 30 C. or alternatively a similar effect may be achieved by conditioning the fibers at 85 percent RH. and then heating the conditioned fibers in a sealed container for about one-half hour less at to C. followed by cooling over a period of about 1 hour or more. In general the upper limit of temperature will be set somewhat below that at which the wool becomes permanently damaged and the lower limit of temperature will be determined solely by economic considerations, i.e., by the time required for satisfactory annealing. As mentioned above, the relative humidity is best chosen to correspond to the regain of the wool under conditions, of normal use, or more specifically, the conditions under which the wool is most likely to undergo wrinkling in use.

Annealing may be carried out under any suitable atmosphere, e.g., air or other gas and it is also within the scope of the method to carry out the treatment in a liquid medium provided the necessary amount of moisture is present.

it is also possible to obtain an annealing effect in the presence of hydrogen bond breaking reagents other than water. The most convenient ways of annealing are-(i) to heat the material '(e.g., wool) in a sealed container of limited volume such that the moisture content of the material remains sensibly unaltered during the treatment; or (ii) to heat the material under conditions where the relative humidity of the airspace is maintained at a constant value. However, despite the advantages which the annealing treatment confers, it has been observed that the improvement obtained by annealing wool in the manner described is not permanent and may be partially or wholly reversed by washing or drying the wool or by operations such as steam pressing. Despite this, however, wool can be reannealed after such treatments and the annealing-deannealing cycle can be repeated at will. It is accordingly a further object of this invention to provide a method for permanently maintaining the wool in the annealed condition, i.e., with the hydrogen bonds in their minimum energy configurations. Such a treatment can be combined with the annealing method of the present invention to produce a permanent setting-effect in wool which greatly improves its resistance to, and recovery from, wrinkling and other undesirable permanent deformation. The combined process can be utilized in conjunctionwith other known treatments to produce so called permanent press wool articleswhich may be machine laundered and dried without losing their shape.

Thus, in accordance with a second main aspect, the present invention provides a method for increasing the resistance of wool fibers to, and their recovery from, deformation which comprises subjecting the wool to the annealing treatment described above, and thereafter subjecting the thus treated wool to a molecular stabilization treatment wherein the wool is reacted with a reagent capable of forming permanent crosslinks between reactive groups in the wool fibers and under conditions which do not substantially deanneal the wool.

The phenomenon of molecular stabilization by cross-linking has been reported in the literature (J R. Cook and J. Delmenico, Test. inst. and [nd., 1968, 6, 153; H. D. Feldtman and B. E. Fleischfresser, ibid i968). Briefly it involves the treatment of wool (or other) fibers with a reagent which is capable of reacting with two or more reactive groups, such as thiol and amino, which are present in wool fiber peptide chain molecules and thereby producing cross-links between such groups. The preferred cross-linking reagents are polyfunctional compounds, i.e., those having two or more functional groups each capable of reacting with a group attached to a wool peptide chain. Many such reagents are known, including, for example, compounds containing combinations of two or more of the following functional groups: and N-methylol, O- and N-alkoxymethyl; activated C- methylol; epoxide; aziridinyl; vinyl, activated vinyl, activated 2-hydroxy ethyl and activated O-derivatives of 2-hydroxy ethyl; active halogen; isocyanate and isothiocyanate; aldehyde; and any of the above in which the functional groups are temporarily blocked or inactivated, but can be regenerated when required. Some of these compounds are more fully described in our copending Pat. application Ser. No. 877,427 filed Nov. 17, 1969. 1

Other suitable cross-linking agents include compounds which, although formally monofunctional, are capable of reacting with more than one reactive group in wool fibers. Formaldehyde is an outstanding example of a suitable compound of this type, but other monoaldehydes and reactive ketones and derivatives thereof may also be useful.

It should be noted, however, that under the cross-linking conditions often employed in the prior art, deannealing of the wool fibers will occur and thus the cross-linking agent and the conditions of its application must be selected carefully so as to at least minimize deannealing of the wool fibers. To this end it may be desirable to apply the cross-linking agent as a gas or vapor or from a solvent, e.g., an organic solvent. [t is also possible, in accordance with this invention, to perform the combined annealing-cross-linking process by the application to the wool of a solution (e.g., an aqueous solution) of a potential cross-linking agent in an unreactive (e.g., protected) form, followed by annealing of the wool and activation of the cross-linking agent.

In some cases better results may be obtained by a multicycle annealing-cross-linking process, i.e., by annealing the wool fibers, treating them with a cross-linking agent and subscquently carrying out a further similar annealing and crosslinking step.

in all cases it is essential to carry out both annealing and cross-linking steps at the appropriate regain of the wool.

The following examples illustrate the practice of the invention and the advantages to be gained thereby.

EXAMPLES l to TREATMENT OF WOOL TABLE 1 Effect of Annealing and Molecular Stabilization on Wrinkle Recovery of Wool Wrinkle Recovery(%) initial" After wetting & pressing Fabric Treatment paral-ICHO under N0. 5 annealing 6| conditions 9. Deannealed as No. 2, treated with 5% paraHCHO under N0, 5 annealing} 54 conditions l0. Partially annealed as in No. l, to give 62% recovery, treated with 5% paraHCHO 50 C., l day, regain equivalent to 65% R.H.

Katz's method (H. J. Katz, Text. Res. J. 1966, 36, 874) Conditioned 30 min, 85%

R.H. 30 C., wrinkled 15 min, 85% R.H. 30C. recovered [5 min. 65 R.H. 21C.

"Treated then held 24 hr. 65% R.H. before measurement Treated, wet out, air dried, steam pressed (as No. 3), held 24 hr 65% R.H. before measurement.

From the above Table it can be seen that the fabric had been stored for sufficient time for it to be in the annealed state. Deannealing by wetting and/or pressing is shown by treatment Nos. 2 and 3 and the last column, treatment Nos. 4 and 5 illustrate the reannealing effect which again was reversed by wetting and pressing. Treatment No. 6 shows the effect of cross-linking deannealed fabric at approximately 0 percent R.H. under conditions which have been used to stabilize set wool to withstand machine washing (as described in our copending patent application). The fabric was even further deannealed and apparently stabilized in that state. Treatment No. 7 indicates that the dry oven treatment destroyed the annealed effect before cross-linking had occurred.

A considerable improvement in wrinkle recovery occurred when annealed fabric was treated (No. 8) with formaldehyde under conditions similar to those which bring accelerated annealing. While wetting and pressing partially destroyed the improvement, the recovery was still better than that of the other wet and pressed fabric,

ln treatments such as No. 8 to ensure that no deannealing occurred during application, the formaldehyde was sprinkled as paraformaldehyde onto the annealed fabric while still at 85 percent and 30 C. Uniform application was obtained by diluting the paraformaldehyde powder with titanium dioxide which in separate experiments was shown to have no effect on wrinkling. The fabrics were then sealed in metal cylinders approx. 7 inches long X 1.5 inches diameter fitter with a solid insert to leave an annular space just sufficient for one thickness of fabric. The 30 minute treatment time included the heatingup period (approx. 10 minutes); increasing the time did not increase the annealing effect. The containers were cooled to room temperature during approx. 1 hour before being opened.

It seems likely that accelerated annealing of the fabric occurred not while it was being heated but during the cooling cycle. The wool was probably partially deannealed at the high temperature and stabilized in that state by cross-linking when formaldehyde was present. During cooling it would have acquired a superimposed temporary effect as with the other fabrics.

Treatment No. 9 indicates that when an unannealed fabric was treated with formaldehyde under annealing conditions (at a regain equivalent to 85 percent R.H.) it was worse than an untreated fabric presumably because cross-linking occurred during heating and before annealing.

It is clear that the optimum cross-linking conditions are not exactly the same as the optimum annealing conditions because the latter occurs during cooling whereas the former occurs during heating. Treatment No. shows that under suitable cross-linking conditions the recovery initially possessed by the fabric can be made fully permanent. An additional temporary annealing effect is superimposed on top of this permanent ef' fect during cooling after the cross-linking treatment. Treatments No. 8 and 10 indicate that better results may be possible by a multicycle process, i.e., by annealing the fabric, treating it with a cross-linking agent to stabilize the initial annealing effect, during which the fabric acquires an additional temporary annealing effect while cooling, and then stabilizing the latter by another cross-linking treatment. This procedure may then be further repeated.

EXAMPLES l l to 13 TREATMENT OF COTTON TABLE 2 Effect of Annealing and Molecular Stabilization on Wrinkle Recovery of Cotton Wrinkle recovery (7: WR,,)

Fabric Treatment after after initial wetting pressing ll. Untreated (straight from 25 27 27 roll) l2. Annealed 60 hr. at 60C. after prior conditioning 37 28 28 at 65% RH l3. Annealed as 12, in the presence of 5% paraHCHO 74 41 3] see footnote (b) table I.

We claim:

l. A method for increasing the resistance to and recovery from deformation of wool textile fibers, which comprises subjecting the fibers to an annealing heat treatment at -l 20 C. and at a moisture regain for the fibers corresponding to 60-95 percent relative humidity for up to about one-half hour, and then cooling the fibers to room temperature over a period ofabout l hour.

2. A method as claimed in claim 1, wherein the treatment is carried out in a fluid medium.

3. A method as claimed in claim 2, wherein the medium is a gas.

4. A method as claimed in claim 1, wherein the treated fibers resulting from the method of claim 1 are subjected to a molecular stabilization treatment in which the fibers are reacted at a moisture regain for the fibers corresponding to that of the first treatment with a creaseproofing agent capable of forming permanent cross-links between reactive groups in the fibers and under conditions wherein the resistance to deformation effected by the first treatment is retained.

5. A method as claimed in claim 4, wherein the creaseproofing agent is a polyfunctional compound having two or more functional groups each capable of reacting with a reactive group in the fibers.

6. A method as claimed in claim 5, wherein the functional grou s are selected from: O- and N-methylol, O- and N-alkoxymet yl and activated C-methylol; epoxide; aziridinyl; vinyl, activated vinyl, activated 2-hydroxy ethyl and activated 0- derivatives of 2-hydroxy ethyl; active halogen; isocyanate and isothiocyanate; and aldehyde.

7. A method as claimed in claim 4, wherein the reagent is formaldehyde or a compound capable of giving rise to formaldehyde under the conditions of the stabilization treatment.

8. A method as claimed in claim 4, wherein the fibers are treated with a solution of a potential cross-linking agent, the fibers are heat treated and the cross-linking agent is subsequently activated to bring about the molecular stabilization.

9. A method as claimed in claim 4, wherein the heat treat ment and molecular stabilization steps are repeated in sequence.

10. The article produced by the method of claim 4. 

2. A method as claimed in claim 1, wherein the treatment is carried out in a fluid medium.
 3. A method as claimed in claim 2, wherein the medium is a gas.
 4. A method as claimed in claim 1, wherein the treated fibers resulting from the method of claim 1 are subjected to a molecular stabilization treatment in which the fibers are reacted at a moisture regain for the fibers corresponding to that of the first treatment with a creaseproofing agent capable of forming permanent cross-links between reactive groups in the fibers and under conditions wherein the resistance to deformation effected by the first treatment is retained.
 5. A method as claimed in claim 4, wherein the creaseproofing agent is a polyfunctional compound having two or more functional groups each capable of reacting with a reactive group in the fibers.
 6. A method as claimed in claim 5, wherein the functional groups are selected from: O- and N-methylol, O- and N-alkoxymethyl and activated C-methylol; epoxide; aziridinyl; vinyl, activated vinyl, activated 2-hydroxy ethyl and activated O-derivatives of 2-hydroxy ethyl; active halogen; isocyanate and isothiocyanate; and aldehyde.
 7. A method as claimed in claim 4, wherein the reagent is formaldehyde or a compound capable of giving rise to formaldehyde under the conditions of the stabilization treatment.
 8. A method as claimed in claim 4, wherein the fibers are treated with a solution of a potential cross-linking agent, the fibers are heat treated and the cross-linking agent is subsequently activated to bring about the molecular stabilization.
 9. A method as claimed in claim 4, wherein the heat treatment and molecular stabilization steps are repeated in sequence.
 10. The article produced by the method of claim
 4. 